FLUVIAL STRATIGRAPHY AND SEDIMENTATION DURING THE HOLOCENE AND LATE PLEISTOCENE AT THE FOXWOOD FARM ARCHAEOLOGICAL SITE (38PN35) ALONG THE OOLENOY RIVER, SOUTH CAROLINA

A 4.8 m sediment column sampled near the boundary between the Piedmont and Blue Ridge in Pickens County, South Carolina provides insight into the history of a fluvial system in the non-glaciated southeastern US. The alluvium consists of a well-defined series of discrete fluvial strata separated by buried soil A-horizons. Radiocarbon and OSL dates indicate the upper half of the sequence, primarily overbank sands, is Holocene in age. Basal sediments, consisting of channel gravels, lateral accretion sands, and clays, were deposited during the late Pleistocene prior to 12.6 ka. Human occupation of the site occurred repeatedly from the early Holocene to the present.

The geomorphic context of the site is a slackwater depositional environment which explains the relatively thick Holocene alluvium. The site lies near the mouth of the Oolenoy and its confluence with the larger South Saluda, allowing high water levels of either river to back up the other, enhancing the deposition of overbank sediments. The site also lies immediately downstream of a topographic knob that protects it from high energy flows during floods. The widening of the floodplain downstream of the knob provides additional impetus for deposition.

The lowermost sediments (320-480 cm depth), deposited during the late Pleistocene, represent a fining upward sequence from channel gravels and sands, through bar sands, to a cap of clays. Overlying strata suggest episodic deposition and erosion throughout the Holocene. Three buried soil A-horizons represent periods of stability or slower deposition. A series of fine to very fine, loamy sands, lacking a fining-upward trend culminates in a buried A-horizon at 250 cm depth, dated to around 12.6 ka. Another set of strata (166-243 cm), again lacking a fining upward trend, leads up to another buried A-horizon, dated to around 10 ka.

The strata from 60-166 cm depth contain a third buried A-horizon that appears to be a slowly aggraded cumulic A. The site’s uppermost strata are a package of medium to fine sands (0-60 cm) with a plow zone, with plow scars visible in places at 15 to 25 cm depth. Apart from archaeological features intrusive into lower strata, cultural materials younger than 2.5 ka are located within the plow zone, indicating erosion, stability, or a limit of aggradation during recent millennia.